The Swedish patent application 78.03046-7 (U.S. patent application 779,152, filed Mar. 18, 1977) contains a description of different embodiments of a device similar to that according to the invention and how the device according to the invention can be applied. The idea behind the present invention is to produce such a device, but which is of a simpler type and which can be made by a simpler method of manufacture.
In U.S. patent applications 787,422, now U.S. Pat. Nos. 4,200,970, and 879,193, filed Feb. 21, 1978 different trimming procedures for devices similar to that according to the invention are described. It should be possible to apply similar trimming procedures for the trimming of the device in accordance with the invention.